1. Field of the Invention
This invention relates to an engine cooling fan for an automotive vehicle and more particularly to a fan driven by an engine and located in a shroud extending from a radiator to the engine.
2. Description of the Prior Art
In an engine cooling system for an automotive vehicle, a fan driven by an engine is often located in a shroud extending from a radiator to the engine to increase the quantity of radiator cooling air flow caused by operation of the fan. In such case, a clearance must be provided between tips of fan-blades and the shroud to avoid interference of the shroud with rotation of the fan, thereby causing objectionable recirculating air flow in the clearance.
Since the recirculating air flow affects the radiator cooling air flow, a ring surrounding the fan is fixedly provided on the tips of the fan blades to form a labyrinth seal in the clearance. The ring and the shroud are preferably provided with portions opposing each other in the axial direction of fan so as to increase the sealing effect in the labyrinth seal. The ring of the fan is also effective in suppressing the generation of a vortex.
However, in such prior art, the portion of the shroud opposing the corresponding portion of the ring of the fan is formed on a rear end thereof as an inwardly extending flange, while the portion of the ring of the fan opposing the flange of the shroud is located on the front side or the rear side of the flange of the shroud. The provision of the flange on the rear end of the shroud increases the manufacturing cost. In addition, when a portion of the ring of the fan is located on the front side of the flange of the shroud, the shroud is required to be of a divisable construction for assembling the vehicle in the plant thereby increasing the manufacturing cost.